This section provides background information related to the present disclosure which is not necessarily prior art to the inventive concepts disclosed and claimed herein.
Internal combustion engines of vehicles, such as automobiles, typically include a combustion chamber where a fuel/air mixture is burned to cause movement of a set of reciprocating pistons, as well as a crankcase which contains the crankshaft driven by the pistons. During operation, it is normal for the engine to experience “blowby,” wherein combustion gases leak past the pistons from the combustion chamber and into the crankcase or cam shaft housing. These combustion or blowby gases typically contain by-products of the combustion process including moisture, acids and an oil mist. Oil mist can further be generated as the result of moving components in the crankcase sloshing hot oil around. It is known for the oil mist to be carried by a crankcase ventilation system to the intake manifold of the internal combustion engine where it is then burned in the combustion chamber along with the fuel/air mixture. This often results in an undesirable increase in oil consumption.
To reduce the unnecessary consumption of oil, it is known to utilize cyclone-type oil separators to remove oil from the oil-laden blowby gases prior to entering the intake manifold. An example of such an oil separator is disclosed in U.S. Pat. No. 6,860,915 to Stegmaier et al. The oil separator includes a housing that defines a chamber. A partition assembly is disposed in the chamber and divides the chamber into an entry segment and an exit segment. The entry segment defines an inlet that extends into the chamber for receiving oil-laden gases from the crankcase, and the exit segment defines an outlet that extends into the chamber for expelling gases to the intake manifold. The partition assembly includes a channel that extends between a first opening in the entry segment and a second opening in the exit segment for passing the oil-laden gases between the entry and exit segments. A spiral member is disposed in the channel. The spiral member defines a helical flow path for guiding the oil-laden gases during passing of the oil-laden gases through the channel to separate the oil from the oil-laden gases. More specifically, small oil droplets pass and coalesce into larger droplets on the inner wall of the channel due to centrifugal forces created as the oil-laden gases pass through the helical flow path. The larger droplets are then directed by gravity to oil outlets and passed to a sump, which generally holds excess oil in the system.
To maximize the amount of oil that is separated by the helical flow path, it is desirable to maintain a relatively high velocity of the oil-laden gases passing therethrough while also providing a relatively large surface area of the inner walls of the channels for the oil to coalesce. Further, it is understood that the flow rate of the crankcase gas inside the helical flow path depends on the quantity of crankcase gas produced per unit time and on the flow cross-section of the flow path. The quantity of crankcase gas produced per unit time is largely related to the speed and load of the engine. To maximize oil separation efficiency, it is known to insert spiral members that have different cross-sectional areas into the channel to provide different flow cross-sections of the helical flow path depending on specific requirements. However, such a method does not actively adjust the effective flow cross-section of the helical flow path as the quantity of crankcase gas produced per unit time varies. Furthermore, oil separators are known to create a high pressure drop between the inlet and outlets, which interferes with the drainage of separated oil. More specifically, the high pressure drop interferes with the force of gravity pulling separated oil particles toward the oil outlets.
In view of the above, there remains a continuing need to develop further improvements to oil separators. Particularly, it remains desirable to provide improvements toward maximizing separation efficiency of oil from the oil laden gases actively during varying low flow and high flow running conditions. It is also desirable to provide an oil separator that has minimal pressure losses between the inlet and outlet. It is further desirable to provide an oil separator that provides greater system design flexibility over conventional oil separator designs.